The practice of postnatal referral of high risk infants between hospitals to obtain appropriate care in the neonatal period is widespread. However, the patterns of utilization of neonatal referral have never been described in detail for a total population, nor have their effects on mortality been appropriately evaluated. In New York City, about 1500 infants, or 1.3% of live births, are annually transferred from their hospitals of birth to hospitals with neonatal intensive care facilities. The proposed study will make use of a unique data resource--linked birth, death and infant transport records for an entire population--to conduct three substudies which examine the process and outcome of neonatal transport. 1) A study of the utilization of transport. 2) A study of the determinants of mortality among transported infants. 3) An examination of the variations in mortality rates among hospitals which vary in their utilization of transport. A fourth objective of this research will be to integrate the results of these analyses with other analyses of newborn care in New York City to draw conclusions on the role of transport in the regionalization of perinatal care.